“What Happened Here Before”
Creating a Bay Timeline
Over
ervview
In this activity students will begin by reading
a poem by Gary Snyder and completing a
homework assignment to learn about his
presentation of the history of California.
Students will then read about the geological
history of the San Francisco Bay and will
work in groups to create an artistic representation of a timeline of the Bay.
Central Questions
What were some of the major events in the
history of California that affected its natural
resources and physical characteristics? What
is the geological history of the San Francisco
Bay and its watershed? What role have plate
tectonics, sedimentation, volcanoes, and
climate change played in the formation of the
Bay?
Estimated Time
Part I: Poetic Review
1 homework assignment
Part II: Artistic Interpretation
1 reading assignment, 1-2 class periods to
create mural
Objectives
Students will be able to:
• Interpret a poem, identifying and
defining key words and phrases, describing a theme, and linking the structure to
the content.
• Describe the history of California and its
wealth of natural resources.
• Comprehend that geology is a dynamic
process.
• Understand how plate tectonics, sedimentation, climate change, and volcanic
activity have shaped the Bay.
• Explain the formation of specific landscapes around the Bay.
Materials
Part I: Poetic Review
For each student:
• 1 copy of student worksheet with Gary
Snyder’s poem “What Happened Here
Before”
Part II: Artistic Interpretation
For each student (for reading assignment):
• 1 copy of “Bay Today, Gone Tomorrow”
For each group (for mural):
• 1 blown-up copy of picture of the Bay
• Ruler
• Pencils
• Art supplies (crayons, color pencils,
paints, etc.)
California Science Content Standards
Grade 6
Standard Set 1.e: major geologic events,
such as earthquakes, volcanic eruptions,
and mountain building result from plate
motions.
Standard Set 1.f: how to explain major
features of California geology in terms of
plate tectonics (including mountains,
faults, volcanoes).
Standard Set 2.a: water running downhill
is the dominant process in shaping the
landscape, including California’s landscape.
Standard Set 2.b: rivers and streams are
dynamic systems that erode and transport
sediment, change course, and flood their
banks in natural and recurring patterns.
Standard Set 2.d: earthquakes, volcanic
eruptions, landslides, and floods change
human and wildlife habitats.
Grade 7
Earth and Life History (Earth Science)
Standard Set 4.a: Earth processes today are
similar to those that occurred in the past
and slow geologic processes have large
92 Save The Bay’s San Francisco Bay Watershed Curriculum
cumulative effects over long periods of time.
Standard Set 4.b: the history of life on Earth
has been disrupted by major catastrophic
events, such as major volcanic eruptions or
the impact of an asteroid.
Standard Set 4.c: the rock cycle includes the
formation of new sediment and rocks. Rocks
are often found in layers with the oldest
generally on the bottom.
Grades 9 - 12
Earth Sciences Standard 9.a: the resources of
major economic importance in California and
their relation to California’s geology.
Language Arts
Grades 6 - 12
Reading
Students read and understand grade-levelappropriate material. (See Standards for details)
Teacher PPrroc
edur
ocedur
eduree
Par
oe
tic Rev
iew
artt I: PPoe
oetic
Review
1. Pass out copies of Gary Snyder’s poem
“What Happened Here Before” and
worksheets as a homework assignment.
Questions:
• What did you think of the poem?
• How did the poem make you feel?
• What are some of the key words you found
and what are their definitions?
• Which key words did you not know before
the presentations and how do they play a
part in the poem?
• What specific images from the poem teach
us about the history of California?
• What do you think is the poet’s message?
• What does the poet seem to think about
how we treat the Earth today?
• What do you predict California will look
like in the future and how would you write
a verse of the poem for the future time
period? (Have the students read some
verses aloud.)
5. The next day in class, lead a discussion
about the poem before collecting the
students’ homework assignments.
2. Tell students that they are to read the poem
carefully at least two times through before
beginning the assignment. Then they
should fill out the worksheet accompanying
the poem. The worksheet requires the
students to find one key word from each
time frame in the poem and do a little
research in the library or on the internet to
define their key word.
3. Give the your class some examples of
appropriate key words, citing a few words
from the vocabulary list. The key words
should be words describing the Earth’s
physical characteristics or natural resources
(examples: slate, schist, manzanita, blacktail
hare, etc.).
4. Each student should answer the following
questions about the poem regarding its
meaning and the meaning of the key phrase
“WE SHALL SEE/WHO KNOWS/HOW
TO BE.”
Par
tis
tic Inter
pr
artt II: Ar
Artis
tistic
Interpr
pree ta tion
Teacher PPrroc
edur
ocedur
eduree
1. Pass out “Bay Today, Gone Tomorrow”
article to students the day before and tell
them to read it for homework.
2. Tell the students to pay special attention to
the geologic processes that shaped today’s
Bay and to create a list of geologic processes
mentioned in the article that have shaped
the Bay.
3. In class the next day, divide class into 4
groups.
4. Pass out art materials to groups.
5. Explain that they are to read the article and
create a free-form artistic mural detailing
the history of the formation of today’s San
Francisco Bay. Their pictures should show
the changes in their time period.
6. Assign each group to a specific time period/
era in the formation of the Bay and have the
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group brainstorm the most important parts
of their time period. Then each group will
design and create their mural on the blownup picture of the Bay.
• Group 1: volcanic eruption and plate
tectonics, Bay Block
• Group 2: river systems, siltation, and
sedimentation process
• Group 3: glaciation and end of ice age
processes, sea level rise and drop
• Group 4: predictions of future
changes….
•
are doing that are affecting the Bay and
its natural resources? (bay fill, wetland
development, water diversion from the
Delta, water pollution)
What are some things that we can do to
protect our resources and prevent the
types of changes we have caused?
Additional Resources
Geologic Bay History
http://squall.sfsu.edu/courses/geol103/labs/estuaries/
partII.html
7. Tell the groups that each group should
create their mural to explain visually the
processes they are assigned. They may use
specific words, phrases, and quotes from the
article. Also, ask them to label their time
period on their mural.
8. When students are ready, have them display
their murals in the room so they can see the
other groups’ work. Ask them what order
the murals should go in to create a timeline
for the history of the formation of today’s
Bay.
9. Have each group present their murals to the
class, explaining what geologic processes
occurred during their time period, etc.
Clas
sion/ W
rap-Up
lasss Discus
Discussion/
Wrap-Up
1. Relate the article by Glen Martin to the
poem by Gary Snyder. Each deals with
almost incomprehensible amounts of time.
How does each writer give us perspective on
our place in geologic time? What are the
similarities and differences between the
poem and the article?
2. Ask the students to make predictions of
what the Bay may look like thousands of
years from now.
• What changes may take place?
• What geologic processes might cause
these changes?
• What are some things that we humans
94 Save The Bay’s San Francisco Bay Watershed Curriculum
“What Happened Here Before”
Par
iterar
ompr
ehension
artt I: LLiterar
iteraryy C
Compr
omprehension
1. Read the poem “What Happened Here Before” by Gary Snyder carefully at
least two times before beginning the assignment. On a separate sheet of paper write out one
key word from each time period within the poem. Do a little research either in the library, on
the internet, or in encyclopedias or dictionaries to define the terms you selected. The terms
selected should be key words within that section of the poem, describing the Earth’s physical
characteristics, natural resources, or wildlife. (examples: schist, manzanita, blacktail hare, etc.)
Par
iterar
artt II: LLiterar
iteraryy Analysis
Answer the following questions on a separate sheet of paper.
1. What do you think is(are) the overall theme(s)/message(s) of this poem?
2. What do you think the poet was trying to achieve by separating the poem into segments of
time?
3. What are the Feather, Bear, and Yuba?
4. What historical event do you think the phrase “tossed up trees and boulders with big hoses” is
referring to?
5. What could “sunlight grown heavy and tasty/ while moving up food-chains/ in search of a body
with eyes and a fairly large/ brain” mean?
6. What do you think the phrase “the land belongs to itself./’no self in self: no self in things’”
means?
7. Interpret the phrase “WE SHALL SEE/ WHO KNOWS/ HOW TO BE.”
8. How did the timeline presented in this poem make you feel?
9. Did you like or dislike the poem? Why?
Save The Bay’s San Francisco Bay Watershed Curriculum 95
WHAT HAPPENED HERE BEFORE
b y Gar
Garyy Sn
Snyyder
— 300,000,000—
First a sea: soft sands, muds, and marls
— loading, compressing, heating, crumpling,
crushing, recrystallizing, infiltrating,
several times lifted and submerged,
intruding molten granite magma
deep-cooled and speckling,
gold quartz fills the cracks—
— 80,000,000—
sea-bed strata raised and folded,
granite far below.
warm quiet centuries of rains
(make dark red tropic soils)
wear down two miles of surface,
lay bare the veins and tumble heavy gold
in streambeds
slate and schist rock-riffles catch it –
volcanic ash floats down and dams the streams,
piles up the gold and gravel—
— 3,000,000—
flowing north, two rivers joined,
to make a wide long lake.
and then it tilted and rivers fell apart
all running west
to cut the gorges of the Feather
Bear, and Yuba.
Ponderosa pine, manzanita, black oak, mountain
yew,
deer, coyote, bluejay, gray squirrel,
ground squirrel, fox, blacktail hare,
ringtail, bobcat, bear,
all came to live here.
—40,000—
And human people came with basket hats and nets
winter-houses and underground
yew bows painted green,
feasts and dances for the boys and girls
songs and stories in the smoky dark.
And where one pays the tax.
(two gents who never used it twenty years,
and before them the widow
of the son of the man
who got him a patented deed
on a worked-out mining claim,)
laid hasty on the land that was deed and acorn
grounds of the Nisenan?
Branch of the Maidu?
(they never had a chance to speak, even,
their name.)
(and who remembers the Treaty of Guadalupe Hidalgo.)
the land belongs to itself.
“no self in self: no self in things”
Turtle Island swims
in the ocean-sky swirl-void
biting its tail while the worlds go
on-and-off
winking
& Mr. Tobiassen, a Cousin Jack,
assesses the county tax.
(the tax is our body-mind, guest at the banquet
Memorial and Annual, in honor
of sunlight grown heavy and tasty
while moving up food-chains
in search of a body with eyes and a fairly large
brain—
to look back at itself
on high.)
now,
we sit here near the diggings
in the forest, by our fire, and watch
the moon and planets and the shooting stars—
my sons ask, who are we?
drying apples picked from homestead trees
drying berries, curing meat,
shooting arrows at bales of straw.
—150—
Then came the white man: tossed up trees and
boulders with big hoses,
going after that old gravel and gold.
horses, apple-orchards, card-games,
pistol-shooting, churches, county jail.
military jets head northeast, roaring, every dawn.
my sons ask, who are they?
We asked, who the land belongs to.
Bluejay screeches from a pine.
WE SHALL SEE
WHO KNOWS
HOW TO BE
96 Save The Bay’s San Francisco Bay Watershed Curriculum
BAY TODAY, GONE TOMORROW
S.F. region’s defining feature is just a transitory puddle in geologic time
by Glen Martin, San Francisco Chronicle Staff Writer
Monday, December 20, 1999
If you had planned to stroll to Ocean Beach 17,000
years ago, you would have been well advised to
pack a lunch. And maybe dinner and the next day’s
breakfast, too.
That’s because the coast was very far away. From
where San Francisco sits, the beach was 26 miles
west, about six miles past today’s Farallon Islands.
The islands themselves, of course, were not islands
at all — they were peaks.
And San Francisco Bay? Well, there was no bay.
And that would remain the case for several thousand years.
The site of the present bay was a series of broad
valleys, each with a tributary stream that poured into
a mighty, sediment-swollen river that originated in
the Sierra Nevada. This river drained through the
Central Valley, the Carquinez Strait, Raccoon Strait
and the stony ramparts that are now the Golden
Gate.
A bay, in fact, is something of an anomaly for the
San Francisco region.
“During the past 600,000 years, the bay has only
existed during three brief periods totaling about
15,000 years,” observes Ken Lajoie, a senior
geologist with the U.S. Geological Survey in Menlo
Park who counts the Bay Area’s geology among his
specialties.
“The present bay has existed near its (current) size
only for the last 4,000 years,” he says. And if the
past is any indication, it will be around for only
another 1,000 years or so.
grinding, compressing and upheaval of tectonic
plates and the inundation of entire landscapes by
vast floods.
It is also a story of life — of primeval forests of
cedar and pine, of great Pleistocene mammals such
as mammoths and giant ground sloths, and of the
people who hunted them with nothing more than
flint-pointed spears.
The very dimensions of the story can’t help but give
one a certain perspective, observes Lajoie, who
notes that even the most dramatic of the Earth’s
features — bays, rivers, mountains — are ephemeral
in the context of geologic time.
‘NOTHING IS PERMANENT’
“We tend to think that the Earth’s features don’t
change, but geologically speaking, the fact is that
nothing is permanent, or even around very long,” he
says.
Today’s bay formed when the last ice age waned. At
the height of the last glaciation about 17,000 years
ago, large amounts of water evaporated from the
oceans and fell as snow, not rain, compacting into
huge continental glaciers. Sea level lowered by
about 300 feet, and big expanses of the present
continental shelf were exposed.
As the glaciers retreated, sea levels began rising,
with rates ranging from three feet per century to 15
feet per century. About 10,000 years ago, the ocean
began sneaking through the Golden Gate, forming
the nascent San Francisco Bay.
“The bay only reached its present size within the
last few hundred years,” says Lajoie.
5,000-YEAR LIFE-SPAN
The geological history of San Francisco Bay is really
the story of several bays — each of which lasted
only about 5,000 years — and of the tens of
thousands of years between, when the land
supported big rivers and lovely valleys.
It is a story that involves the cataclysmic raising and
lowering of the Pacific Ocean, stupendous volcanic
eruptions, the creation of mountains through the
Even while the melting glaciers worked to form a
large bay, other factors conspired to restrict its size.
“The bay would be about twice its present size if
sediments hadn’t partially filled the subsiding basin
it now occupies,” Lajoie observes.
But to understand the forces that shaped the bay,
you have to go further back in time — close to a
million years further.
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The sedimentary record indicates that the interior of
California didn’t always drain through the bay basin,
as is now the case. Minerals from the Sierra Nevada
began appearing in the basin somewhat less than
600,000 years ago — a blink in the context of
geological time.
Prior to that, a vast inland sea called Corcoran Lake
occupied much of the Central Valley, draining
through the Salinas River into Monterey Bay.
VOLCANIC ERUPTION
About 760,000 years ago, a tremendous volcanic
eruption occurred in what is now the Bishop area. A
great caldera was created, and massive amounts of
volcanic ejecta were deposited in the lake.
But this ash didn’t make it into the bay until tectonic
shifting in the Earth’s crust caused the Bay Area to
subside and the south end of the lake to rise about
560,000 years ago.
This caused the lake to spill over the ridge that
separated it from the bay basin. The flow carved the
Carquinez Strait and drained the lake. It could have
happened so fast that it would have been a single,
catastrophic event, says Lajoie — a great gush of
water roaring to the sea.
Since then, tectonic activity — upthrusting of the
Earth’s crust — has plugged the Central Valley’s
outlet through the Salinas River. Now, everything
that flows into the Sacramento and San Joaquin
valleys ultimately pours out the bay.
Another eruption, this from Mount Lassen and
much smaller than the Long Valley Caldera near
Bishop, also contributed sediments to the bay.
“This occurred about 435,000 years ago,” says
Lajoie. “Sediments from the event are called the
Rockland Ash, and can be seen clearly in the sea
cliffs at Fort Funston on the San Francisco coast.”
As the ice from the last glaciation melted, the
Sacramento and San Joaquin rivers became great,
braided streams choked with sediment.
“All that glacial outwash was dumped in the Central
Valley and the Delta,” says Lajoie. “There was so
much sediment that huge dune fields blew out of the
river near Antioch about 15,000 years ago. The same
thing happened where Oakland now sits.”
time, but those sediments ultimately covered much
of the bay basin.
SOURCES OF SILT
A good deal of fine silt and clay still comes into the
bay from the Sacramento-San Joaquin river system.
But the lion’s share of sediment — mostly sand and
gravel — issues from Alameda Creek, which drains
Livermore Valley through Niles Canyon.
“Many people find that surprising,” says Lajoie,
“because the biggest source of ongoing bay
sedimentation isn’t even directly adjacent to the bay
— it’s Livermore Valley. There’s a huge alluvial fan
of sediment deposited by Alameda Creek that
spreads out beneath the bay from the Coyote Hills
to the shore of Palo Alto.”
Other things have helped the bay become a prime
sediment trap — things of a tectonic nature.
Mountains have built on both the San Andreas and
Hayward faults, sharply defining the limits of the
estuary. The process continues today, with the
continuing uplifting of the Santa Cruz Mountains,
which straddle the San Andreas Fault.
Simultaneously, the land just west of the Hayward
Fault is subsiding; meanwhile, structural rock
underlying the South Bay is slowly sinking and
gradually tilting eastward.
As the Santa Cruz Mountains and the Berkeley Hills
ascend, they are squeezing the zone of bedrock
between them, known as the Bay Block.
“The interesting thing about the Bay Block is that it
is basically free of faults at this point,” observes
Lajoie. “But as it continues to be compressed, it
might eventually develop new fault lines.”
CHANGES CONTINUE
The change has been dizzying — and it won’t abate.
It will continue, regardless of the level of human
activity. Erosion and plate tectonics will grind on
inexorably. And another ice age is not merely likely,
Lajoie observes — it is inevitable.
Lajoie says there is increasing evidence to indicate
that ice ages are triggered by perturbations in the
Earth’s orbit, subtle movements caused by the
gravitational effects of Jupiter and our moon.
MASSIVE AMOUNTS OF DUST
Oakland, in fact, is built over a deposit of dune sand
known as the Merritt Sand. There was no bay at that
“The planets formed by sweeping up massive
98 Save The Bay’s San Francisco Bay Watershed Curriculum
amounts of dust and debris when the solar system
formed, but a lot was left over,” says Lajoie. “It
appears concentrated in a disk around the sun.”
THE MAKING OF A BAY
The Earth’s orbital plane tips through this debris
disk every 100,000 years or so, Lajoie observes. The
dust occludes sunlight, reducing the amount of
thermal energy that reaches the planet’s surface.
Three geological processes have shaped San
Francisco Bay: the rise and fall of sea level, the
shifting of tectonic plates and the deposition of
sediment from rivers. All work in concert to form an
estuary that is in constant flux — and that periodically disappears for tens of thousands of years.
That probably isn’t enough to start an ice age by
itself, he says.
— Sea Level Rise
“The oceans distribute solar energy globally, but the
margins are very fine,” he said. “The orbital parameters can’t do it by themselves — but they’re
triggers. When the balance is finally thrown off in
the oceans, glaciation can occur very quickly.”
But what about global warming? Couldn’t the
ongoing atmospheric loading of heat-trapping gases
like carbon dioxide forestall another ice age and
guarantee the longevity of the bay, orbital wobbles
notwithstanding?
Lajoie doesn’t think so.
“I’d prefer that we maintain a cautious attitude
about releasing greenhouse gases, but I don’t think
they could overcome the orbital signal,” he says. “I
think it’s just too strong.”
During the height of the last Ice Age 17,000 years
ago, sea level dropped by 300 feet, and there was
dry land west of what is now the Farallon Islands.
Melting glaciers caused sea levels to rise, and the
current bay began to form around 10,000 years ago.
It has existed near its current size only for the the
last 4,000 years.
—The Bay Block
Shifting tectonic blocks continue to shape the bay.
The rising Santa Cruz Mountains and Berkeley Hills
are compressing the Bay Block, a vast slab of
Franciscan rock underlying the south bay and its
sediments. Though the Bay Block is essentially free
of faults, it is expected that this compression will
ultimately cause new faults to form.
Our distant descendants, then, might well have to
forgo bay views if they plan to live in San Francisco.
CORCORAN LAKE
“When glaciation occurs, the bay drains, and
everybody ends up walking to the Farallones,”
Lajoie says.
About 760,000 years ago, much of California’s
Central Valley was a great freshwater inland sea
known as Corcoran Lake. The lake’s outlet was
the Salinas River, ultimately draining to Monterey
Bay.
Then about 560,000 years ago, tectonic uplifting
allowed the lake to rise sufficiently to cut through
the soft soils of what is now the Bay Area. The
Carquinez Strait was rapidly carved.
The uplifting also plugged the Salinas Valley
outlet, leaving San Francisco Bay as the Central
Valley’s only outlet. Sediment deposited by
Central Valley rivers limits the size of the bay.
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